DE (Dynamics Explorer)

Pre-launch photo of the DE-1/DE-2 spacecraft stack
before being covered by their fairings and mated with the Delta launch
vehicle. DE-1 is on the bottom

Dynamics Explorer is a NASA mission, launched on August 3, 1981, involving two spacecraft to
study the interaction between the hot, thin, convecting plasma of Earth's magnetosphere and the cooler, denser
plasmas and gases co-rotating in the ionosphere and upper atmosphere. DE 1 and DE 2 were launched together and placed in
polar coplanar orbits to allow simultaneous measurements at high and low
altitudes in the same field-line region.

The spacecraft approximated a short polygon 137 cm in diameter and 115 cm
high. The antennas in the x-y plane measured 200 m tip-to-tip,
and on the z-axis 9 m tip-to-tip. Two 6-m booms were provided for
remote measurements. Science operations continued over a nine-year period
until terminated on October 22, 1990. The spacecraft were also known as Explorer 62 and 63.